Rapid development of the current industry causes huge energy consumption, and the overexploitation of petroleum makes an energy problem increasingly prominent. In order to ease the energy problem, development of renewable energy becomes a necessary means. In recent years, research on preparation of biodiesel and aviation kerosene from animal and vegetable oil through a hydrogenation method emerge continuously. Castor is an oil-production crop with easy growth and high oil yield, and meanwhile castor oil is not edible, so the castor oil can be used as a good raw material for preparing biological aviation kerosene and has broad application prospects.
A main component of aviation kerosene is a mixture of straight-chain and branched-chain alkanes with a carbon number of 8-16. The branched-chain alkanes are the main components of aviation kerosene due to the influence of freezing points. Standards of the aviation kerosene (from ASTMD7566) include: a freezing point smaller than −47°, a flashing point greater than 38° C. a viscosity smaller than 8.0 mm2S−1, a boiling point between 200-300° C. a sulfur content smaller than 20 ppm, an olefin content smaller than 2%, and a content of aromatic hydrocarbon smaller than 1%. It is known that the biological aviation kerosene made from Jatropha curcas has a freezing point of −49° C. a flashing point of 44° C. viscosity of 4.3 mm2S−1, a boiling point between 200-300° C. and the content of sulfur, olefin and aromatic hydrocarbon of zero. The main component of the castor oil is glyceride of 9-alkenyl-12-hydroxyoctadecanoic acid. First, a hydroxyl group and double bonds are removed from the castor oil through hydrodeoxygenation to generate straight-chain alkanes with carbon numbers of 17 and 18. Then through isomerization and cracking reactions in the presence of a selected appropriate catalyst, the carbon chain is isomerized and cracked into straight-chain and branched-chain alkanes with a carbon number of 8-16. Therefore, in the hydroisomerization and cracking reactions, the selectivity to the product is of vital importance. Only by selecting an appropriate carrier and active component, the high-yield aviation kerosene component can be obtained.
Chinese patent CN101952392A discloses a method for preparing aviation fuel from renewable raw materials such as vegetable oil and animal fat. The raw materials are contacted with a hydrodeoxygenation catalyst to prepare straight-chain alkanes, then contacted with an isomerization catalyst to isomerize at least part of straight-chain alkanes to generate branched-chain alkanes and then contacted with a selective cracking catalyst to obtain C8-C16 alkanes, CN102482595A discloses a method for producing a base material of aviation fuel oil. By hydrogenating the animal fat and the vegetable oil as the raw materials through a catalyst with a hydrodeoxygenation function and hydroisomerizing the raw materials, the aviation fuel is obtained. CN102676203A discloses a method for preparing biomass aviation fuel by using the Jatropha oil, rubber seed oil, palm oil and swill-cooked dirty oil as raw materials through processes of double-bond oxidation, hydrolysis and decarboxylation reactions. CN102994138A discloses a method for preparing biological aviation kerosene by using the swill-cooked dirty oil as a raw material. CN201410080542.4 discloses a catalyst for preparing aviation kerosene from castor oil and a preparation method thereof. The preparation method mainly adopts 3-aminopropyltriethoxysilane and citric acid to modify the hydrodeoxygenation carrier, and simultaneously introduces Fe as an additive of the hydrodeoxygenation catalyst. CN201510038506.6 discloses a preparation method of hydrodeoxygenation and hydroisomerization catalysts for preparing biological aviation kerosene from castor oil, which mainly includes the modified MCM-41 as the carrier of the hydrodeoxygenation catalyst; and for the hydroisomerization catalyst, the modified SAPO-11 is selected as the carrier, and the selected active component is one of Pt, Pd or Ni.
Although reports of the above literature provide a possibility of preparing biological aviation kerosene by using biomass as raw material, there are still problems of complex production processes, low catalyst activity, poor product selectivity, high cost and low catalytic efficiency, and particularly a problem of difficulty in obtaining high-yield biological aviation kerosene.